The invention relates to a brake pad of a disc brake.
As is known, the friction pads of brake pads are subject to operation-induced wear which is monitored for reasons of operational safety, with the result that the brake pad can be replaced at the latest when a minimum thickness of the friction pad has been reached.
In order to monitor the wear of the friction pad, an electrical wear end indicator is used. The electrical wear end indicator has a sensor which is inserted on the edge side into the pad carrier plate of the brake pad and is connected via electrical cables to an evaluation unit.
DE 10 2006 034 764 A1 discloses and describes a brake pad of the generic type, which is equipped with a pad-retaining spring supported on an outer edge region of the pad carrier plate and which is connected nonreleasably to the pad carrier plate by means of a hood or cover.
In the mounted functional position of the brake pad, that is to say when it is installed in a disc brake, a retaining clamp or bar, which is clamped with a brake caliper of the disc brake is supported on the pad-retaining spring and/or on the hood. The brake pad is pressed under spring prestress into a pad carrier support of a vehicle-side brake carrier.
The above-mentioned sensor of the wear end indicator is held captively by the pad-retaining spring, since the pad-retaining spring is positioned in such a way that the displacement travel, that is to say the insertion travel, of the sensor is limited correspondingly.
Usually, brake pads of the concerned type have up to now been preassembled, that is to say including the wear end indicator. Here, the sensor is also secured against loss by the pad-retaining spring in the not yet mounted position of the brake pad. However, this results in some disadvantages, since mounting and dismantling of the sensor is no longer possible when the cover is already inserted and connected to the pad carrier plate. This has the consequence that it is not possible to replace the sensor in the installed position of the brake pad, for example if the sensor is defective, with the result that the entire brake pad has to be replaced.
In addition, correspondingly extensive stockpiling of brake pad sets is required since, as mentioned, the brake pads are preassembled completely on account of the nonreleasable fastening of the pad-retaining spring to the pad carrier plate.
The invention is therefore based on the object of developing a brake pad of the above-described type in such a way that it can be produced and mounted more simply and cheaply.
This object is achieved by a brake pad of a disc brake, in particular for a commercial vehicle, having a pad carrier plate which carries a friction pad and to which a pad-retaining spring, which can be moved in the clamping direction relative to it, is connected nonreleasably by means of a hood fastened thereto. An electrical wear end indicator is connected with a sensor which is inserted on the edge side. The sensor is held captively in the mounted position of the brake pad by the pad-retaining spring, which is pressed down by way of a pad-retaining clamp. When the pad-retaining clamp is dismantled and therefore in a relieved or largely relieved position of the pad-retaining spring, the spacing of the mounted pad-retaining spring from the pad carrier plate in the region of the sensor is equal to or greater than the associated height dimension of the sensor.
As a result of this design embodiment, there is the possibility to mount the wear end indicator and/or its sensor even if the pad-retaining spring has already been connected nonreleasably to the pad carrier plate. This affords considerable advantages over the prior art. Thus, for example, it is possible to replace the sensor if the latter is defective, without it being necessary to change the entire brake pad. Naturally, there is a certainly remarkable cost saving as a result, provided that the brake pad is otherwise still functional, that is to say the friction pad is not yet worn out correspondingly.
In order to replace the sensor in an installed brake pad, only the pad-retaining clamp which is supported on the pad-retaining spring, is to be released, with the result that the pad-retaining springs are relieved and the sensor can be pushed into the intermediate space formed between the pad-retaining spring and that edge of the pad carrier plate which is assigned to the pad-retaining spring and can subsequently be removed.
However, not only is the replacement of a sensor possible without problems as a result of the invention, but rather also the retrofitting of the brake pad which is in this respect preassembled as a structural unit and in which the pad-retaining spring has already been connected nonreleasably to the pad carrier plate and the friction pad is fastened thereto. These preassembled brake pads can then be equipped with the sensor only when required. This results in cost-reducing simplified stockpiling, and also flexible, tailored equipping of the brake pad.
There is provision according to one advantageous embodiment of the invention for the spacing of the mounted pad-retaining spring from the pad carrier plate in the relieved or largely relieved position, which spacing is equal to or greater than the associated height dimension of the sensor, to be fixed by mutually corresponding stops of the pad carrier plate on one side and the hood or cover on the other side.
Here, the hood or cover is connected to the pad carrier plate in a radially displaceable manner. A slot can be provided, for example, in the hood or cover as a stop, in which slot a pin of the pad carrier plate is guided, the slot extending in the clamping direction of the pad-retaining spring.
However, one or more grooves may be provided in the pad carrier plate, which grooves likewise extend in the clamping direction of the pad-retaining spring and into which projections of the hood or cover engage.
Further advantageous embodiments of the invention are described herein.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.